Pavement Preservation

Checklist Series

2 ChipSealApplication

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Chip SealApplication Checklist

This checklist is one of a series created to guideState and local highway maintenance andinspection staff in the use of innovativepavement preventive maintenance processes. The series is provided through the joint efforts ofthe Pavement Preservation Program of theFederal Highway Administration (FHWA), andthe Foundation for Pavement Preservation (FP2).

FHWA uses its partnerships with FP2, theAmerican Association of State Highway andTransportation Officials, and State and localtransportation agencies to promote pavementpreservation.

To obtain other checklists or to find out moreabout pavement preservation, contact your localFHWA division office or FP2 (at www.fp2.org),and check into these FHWA Web pages:

www.fhwa.dot.gov/preservation

www.fhwa.dot.gov/infrastructure/asstmgmt/resource.htm

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Chip Seal Application 1

Chip SealApplication Checklist

PreliminaryResponsibilities

Project Review Is the project a good candidate for a chip seal?How much rutting is present?How much and what type of cracking exists?Is crack sealing needed?How much bleeding or flushing exists?Review project for bid/plan quantities.

Document ReviewBid specificationsSpecial provisionsConstruction manualTraffic control plan Agency requirementsManufacturer�s instructionsMaterial safety data sheets

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Materials ChecksThe type of asphalt emulsions to be used iscompatible with the aggregate.The asphalt is from an approved source (if required).The asphalt is sampled and submitted fortesting (if required).All aggregate chips are close to the samesize.The aggregate is clean and free of excessfines.The asphalt application temperature range is specified.

Chip Seal Application 2

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Preapplication InspectionResponsibilities

Surface PreparationThe surface is clean and dry.All pavement distresses have been repaired.The existing surface has been inspected fordrainage problems.

Equipment Inspections

Distributor

The spray bar is at the proper height.All nozzles are uniformly angled 15o to 30o

from the spray bar.All nozzles are free of clogs.The spray pattern has been checked foruniformity and proper overlap (double or triple).The application pressure has been checked.The distributor�s application calibration hasbeen checked.

Chip Spreader

Each gate control and setting has beenchecked.The scalping screen is in good condition.The chip spreader�s calibration across theentire chipper head has been checked.The truck hookup hitches have been checked.

Chip Seal Application 3

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Haul Trucks

The truck box is clean and free of debris andother materials.The truck hookup hitch is in working order.If required, a truck box apron or extension forloading the chip spreader is in place.

Rollers

The type of roller to be used has beenselected (pneumatic-tired rollerrecommended).The roller tire size, rating, and pressurecomply with the manufacturer�srecommendations.The tire pressure is the same on all tires.All tires have a smooth surface.

Broom

The bristles are the proper length.The broom can be adjusted vertically to avoidexcess pressure.

All Equipment

All equipment is free of leaks.All equipment is calibrated and clean.

Chip Seal Application 4

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Weather RequirementsThe agency has a range of dates when chipsealing can be done.Air and surface temperatures have beenchecked at the coolest location on the project.Air and surface temperatures meet agencyrequirements.Application of asphalt does not begin if rainis likely.High winds can create problems with asphaltapplication.High temperatures, humidity, and wind willaffect how long the asphalt/emulsion takes tobreak.

Determining Application RatesAgency guidelines and requirements arefollowed.A chip seal design has been done.More asphalt is applied to dried-out andporous surfaces.More asphalt is applied on roads with lowtraffic volumes.Less asphalt is applied to smooth, nonporous,and asphalt-rich surfaces.Less asphalt is applied on roads with hightraffic volumes.There is a salt and pepper appearance afterthe aggregate has been applied.

Chip Seal Application 5

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Checking Application Rates

Asphalt - Method A(RECOMMENDED FOR CALIBRATION)

Record the weight of a .84 m2 (1 yd2) pan ornonwoven geotextile material.Place the pan or geotextile on the roadsurface.Have the distributor apply asphalt over thepan or geotextile.Record the weight of the pan and asphalt orthe geotextile and asphalt.Subtract the two weights to obtain the weightof the applied asphalt.

Asphalt – Method B (RECOMMENDED FOR RANDOM CHECKS)

Park the distributor on level ground, measurethe asphalt, and recover the number of L (gal)area of asphalt (note: not a conversion).Measure off a known area for a test section.Have the distributor apply asphalt to the testsection.Park the distributor on level ground andremeasure and record the L (gal) of asphalt.Subtract the two numbers to obtain the L(gal) of asphalt applied.Divide the L (gal) applied by the areacovered by asphalt. The result equals theapplication rate: L/m2 (gal/yd2). (If using feet,length x width/9 = yd2.)

Chip Seal Application 6

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Aggregate – Method A (RECOMMENDED FOR CALIBRATION)

Weigh a .84 m2 (1 yd2) tarp or geotextilematerial.Place the tarp or geotextile on the roadway.Have the chip spreader apply the aggregateover the tarp or geotextile.Weigh the tarp or the geotextile material withthe aggregate.Subtract the two weights to obtain the weightof the aggregate.Divide the weight of the aggregate by .84 m2

(1 yd2) to determine the application rate.

Aggregate – Method B (RECOMMENDED FOR RANDOM CHECKS)

Weigh a haul truck empty.Load the haul truck with aggregate andreweigh the truck.Subtract the two weights to obtain the weightof the aggregate.Empty all the aggregate into the chipspreader.Have the chip spreader apply all theaggregate from the weighed truck.Measure the length and width of theaggregate spread and calculate the area (ifusing feet, length x width/9 = yd2).Divide the weight of the chips by the area ofspread to determine the actual application rate(kg/m2 or lb/yd2).

Chip Seal Application 7

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Traffic ControlThe signs and devices used match the trafficcontrol plan.The setup complies with local agencyregulations or the Federal Manual onUniform Traffic Control Devices (MUTCD).Flaggers do not hold the traffic for extendedperiods of time.The pilot car leads traffic slowly�40 kph (24mph) or less�over fresh seals.Signs are removed or covered when they nolonger apply.Any unsafe conditions are reported to asupervisor.

Chip Seal Application 8

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Chip Seal Application 9

Project InspectionResponsibilities

Asphalt ApplicationBuilding paper is used to start and stopasphalt application for straight edges.The asphalt temperature is within the requiredapplication range.The application looks uniform.A check is made for plugged nozzles.A check is made for drilling or streaking.Random checks of application rates areperformed.The distributor speed is adjusted to match thechip spreader speed to prevent stop-startoperations.The distributor is stopped if any problems are observed.

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Chip Seal Application 10

Aggregate ApplicationEnough trucks are on hand to keep a steadysupply of aggregate for the spreader.The application starts and stops with neat,straight edges.The application starts and stops on buildingpaper.The chip spreader follows closely�30 m (33 yd) or less�behind the distributor whenan emulsion is used.The spreader travels slowly enough toprevent chips from rolling when they hit the surface.The aggregate is in a surface-damp condition.No asphalt is on top of the chips.The application is stopped as soon as anyproblems are detected.The application appears uniform.The aggregate has a salt and pepperappearance.The percentage of aggregate embedment inthe asphalt is checked and the asphalt oraggregate application rate adjusted ifrequired.A check is made for streaks and plug-ups.

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Truck OperationTrucks are staggered across the fresh sealcoat to avoid driving over the same area.Trucks travel slowly on the fresh seal coat.Stops and turns are made gradually.Truck operators avoid driving over exposedasphalt.Trucks stagger their wheel paths whenbacking into the chip spreader to helpeliminate aggregate rollover and to aid in rolling.

RollingThe rollers follow closely behind the chipspreader.The rollers� first pass is on the meetline.The rollers travel slowly�speeds are kept at8 kph (5 mph) maximum.Rollers must avoid driving on exposedasphalt.All stops, starts, and turns are madegradually.The entire surface is rolled twice.

Chip Seal Application 11

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Chip Seal Application 12

Longitudinal JointsThe meetline is only as wide as the sprayfrom the end nozzle�about 20 cm (8 in).The distributor lines up so that the end nozzlesprays the meetline.The meetlines are not made in the wheelpaths.The meetlines are made at the center of theroad, center of a lane, or edge of a lane.The meetlines are not left uncoveredovernight.

Method A

Leave a 15�20 cm (6�8 in) strip of asphaltexposed when applying the aggregate.Apply asphalt to the strip on the nextdistributor�s pass.Apply aggregate to the asphalt.

Method B

Turn the end nozzle 90o.Apply asphalt and aggregate the full width ofthe binder.Repeat the process on subsequent passes.

Transverse JointsAll asphalt applications begin and end onbuilding paper.All aggregate applications begin and end onbuilding paper.The building paper is disposed of properly.

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BroomingBrooming begins as soon as possible.Brooming does not dislodge the aggregate.Brooming does not begin until a sufficientbond is formed between the aggregate andthe asphalt. Check the asphalt manufacturer�srecommendation or refer to agencyrequirements.Consider using a flush truck to place wateron the surface before brooming to reducedust problems.

Opening the Chip Seal to Traffic

The traffic travels slowly�40 kph (25mph)�or less over the fresh seal coat until itis broomed and opened for normal traffic.Reduced speed limit signs are used whenpilot cars are not used.After brooming, pavement markings areplaced before opening pavement to normaltraffic.All construction-related signs are removedwhen opening pavement to normal traffic.

Cleanup ResponsibilitiesAll loose aggregate from brooming isremoved from the travelway.Excessive asphalt application and spills are removed.

Chip Seal Application 13

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Common Problems and Solutions

(Problem: Solution)Aggregate embedment over 80 percent:Consider lowering the asphalt applicationrate.Aggregate embedment less than 50percent: Consider raising the asphaltapplication rate.Lots of chips with small amounts ofasphalt on them: Consider lowering theaggregate application rate.Excessive asphalt splattering: The spraypressure is too high.Streaking or drill marks in asphalt:1. Asphalt is too cold.2. Viscosity of the asphalt is too high.3. All the nozzles are not at the same angle.4. Spray bar is too high.5. Spray bar is too low.6. Spray bar pressure is too high.7. Nozzle is plugged.Exposed aggregate remains after aggregateapplication: Chip spreader gate may beclogged or malfunctioning.Excessive aggregate: Spreader gate may bemalfunctioning or chipper head may beoverloaded.

Chip Seal Application 14

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Uneven aggregate application: Recalibratethe chip spreader; gates may not all be set thesame.Asphalt on top of the aggregate:1. Chip spreader may be operating too fast.2. Truck, roller, or pilot car may be

operating incorrectly.Chips being dislodged:1. Asphalt application rate is too low.2. Aggregate is dirty or dusty.3. Traffic or equipment speeds are too high.4. Brooming has been started before the

asphalt is properly set.Asphalt bleeding or flushing: Asphaltapplication rate is too high.Loss of aggregate at meetlines afterbrooming: Check meetline procedures.

Chip Seal Application 15

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Chip Seal Application 16

SourcesInformation in this checklist is based on or refersto the following sources:

Manual on Uniform Traffic Control Devices,Millennium Edition. 2000. Washington, DC:Federal Highway Administration.

An Overview of Surface RehabilitationTechniques for Asphalt Pavements. Pub. No.FHWA-PD-92-008. 1992. Washington, DC:Federal Highway Administration.

Thin-Surfaced Pavements, Synthesis of UserPractices, NCHRP Synthesis 260. 1998.Washington, DC: Transportation ResearchBoard, National Cooperative HighwayResearch Program.

For more information about pavementpreservation, visit these Web sites:

www.fhwa.dot.gov/preservation

www.fhwa.dot.gov/infrastructure/asstmgmt/resource.htm

www.fp2.org

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For more information on the PavementPreservation Checklist Series, contact:

Construction and System Preservation TeamOffice of Asset ManagementFederal Highway Administration, HIAM-20U.S. Department of Transportation400 Seventh Street, SW, Room 3211Washington, DC 20590E-mail: preservation@fhwa.dot.govTelephone: 202-366-1557

National Center for Pavement PreservationMichigan State University2857 Jolly RoadOkemos, MI 48864E-mail: galehou3@msu.eduTelephone: 517-432-8220www.pavementpreservation.org

Foundation for Pavement Preservation 8613 Cross Park DriveAustin, TX 78754E-mail: fppexdir@aol.comTelephone: 866-862-4587 (toll free)www.fp2.org

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September 2002

Publication No. FHWA-IF-02-046

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